The willingness of a seat occupant to put on a seatbelt may depend on the wear comfort of the seatbelt. It is therefore possible, for example, for a seatbelt which is incorrectly set in terms of height to run along the neck of the seat occupant instead of over their shoulder. On the one hand, a seatbelt which has been put on in such a way can represent, in the case of an accident, a safety risk for the occupant, since injuries to the neck caused by the seatbelt may result, and on the other hand the seatbelt running along the neck can also cause skin irritation on the neck and therefore result in poor wear comfort. For example it is frequently found in the case of children that they wear the seatbelt under their arm instead of over their shoulder, which constitutes an even greater safety risk in the case of an accident, since the safety belt then has a significantly restricted restraining capacity. A seatbelt which runs along the neck or a seatbelt which is being worn under an arm, in other words a seatbelt which has not been put on according to regulations, constitutes here an accident-related safety-relevant wear-comfort property of the seatbelt.
U.S. Pat. No. 6,952,974 B2 discloses, for example, the use of a seatbelt tension sensor for a seatbelt of a seat occupant, in order to be able to control an ignition property of an airbag as a function thereof, by automatically detecting whether a child's seat has been positioned on the vehicle seat (relatively high seatbelt tension) or an occupant is sitting on it (relatively low seatbelt tension).
Furthermore U.S. Pat. No. 7,519,461 B2 discloses a system for classifying seat occupant by using a plurality of sensors arranged under a seat cushion of the vehicle seat, and a seatbelt tension sensor.
A detection system, equipped with a plurality of sensors, for a seat occupant is also known from U.S. Pat. No. 7,100,980 B2. The sensors are arranged in a seat cushion of the vehicle seat.
A further device for detecting an occupied state of a seat is described in DE 20 2004 001 895 U1.
U.S. Pat. No. 7,708,341 B2 discloses a vehicle seat for determining a sitting position of an occupant sitting therein.
Generally, seatbelt systems which output an optical and/or acoustic warning signal when a seatbelt has not been put on during a journey are also known from the prior art.